The present invention relates to hydraulic booster devices for the brake circuit of motor vehicles.
Such a device is described, for example, in U.S. Pat. No. 4,858,438, to which reference will be made as regards its functioning.
It is known that such a device comprises a body pierced with a bore, in which slide coaxially a pusher controlled by a brake pedal and a piston means located between first and second chambers containing a brake fluid, the first chamber receiving at least one spring which loads the pusher and the piston means away from one another, the first and second chambers being connected respectively to sources of fluid under low pressure and under high pressure by valve means.
The spring provided in the first chamber constitutes a stroke simulator for the pedal which is generally connected to the pusher by means of a mechanism forming a lever.
When the pedal is depressed, the spring of the first chamber is compressed. The energy accumulated in this spring is restored when the driver releases his force on the pedal.
If he releases this force gently, the return movement of the pusher is damped by the driver's foot. In contrast, if the driver simply releases his force suddenly, for example by sliding his foot off the pedal, the energy accumulated in the spring will be transmitted abruptly, in the form of kinetic energy, to the pusher/pedal/mechanism assembly forming a lever, and this will have to be absorbed by the mechanical connections between these components.
In some cases, this can cause damage to or destruction of these connections.